Add the Romania (ro) regime

[adlrocha]

This PR adds the Romania (ro) tax regime to comply with the latest fiscal measures taking effect in 2025, including the increase in VAT rates and the extension of the RO e-Factura system to B2C and simplified invoices.

Pre-Review Checklist

• I've read the CONTRIBUTING.md guide.
• I have performed a self-review of my code.
• I have added thorough tests with at least 90% code coverage.
• I've modified or created example GOBL documents to show my changes in use, if appropriate.
• When adding or modifying a tax regime or addon, I've added links to the source of the changes, either structured or in the comments.
• I've run go generate . to ensure that the Schemas and Regime data are up to date.
• All linter warnings have been reviewed and fixed.
• I've been obsessive with pointer nil checks to avoid panics.
• The CHANGELOG.md has been updated with an overview of my changes.
• Requested a review from @samlown.

[codecov]

Codecov Report

❌ Patch coverage is 94.02985% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.72%. Comparing base (bf0c5f8) to head (5c30013).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
regimes/ro/bill_invoice.go	94.87%	2 Missing and 2 partials ⚠️
regimes/ro/org_identities.go	92.30%	2 Missing and 2 partials ⚠️
regimes/ro/tax_identities.go	87.09%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #669      +/-   ##
==========================================
+ Coverage   92.71%   92.72%   +0.01%     
==========================================
  Files         318      323       +5     
  Lines       15793    15994     +201     
==========================================
+ Hits        14642    14831     +189     
- Misses        826      832       +6     
- Partials      325      331       +6     

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[Copilot]

Pull request overview

This PR introduces the Romania (ro) tax regime to GOBL, implementing comprehensive support for Romanian fiscal requirements including the 2025 VAT rate changes mandated by Law 141/2025. The implementation covers VAT management, identity validation (CUI/CIF for businesses and CNP for individuals), invoice validation, and correction document types (credit notes, debit notes, corrective invoices).

Key changes:

• VAT rates: 21% standard and 11% reduced (effective August 1, 2025), with historical rates (19%/9%/5% for 2017-2025, 20% for 2016, 24% for 2010-2015)
• Identity validation: CUI/CIF with modulo 11 checksum algorithm and CNP with 13-digit validation
• E-invoicing compliance: Support for B2B, B2C, and simplified invoice mandates per Law 296/2023, OUG 69/2024, and OUG 138/2024

Reviewed changes

Copilot reviewed 25 out of 34 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
regimes/ro/ro.go	Main regime definition and entry point with validator and normalizer functions
regimes/ro/tax_categories.go	VAT rate definitions (standard, reduced, super-reduced) with historical values
regimes/ro/tax_identities.go	CUI/CIF validation with modulo 11 checksum algorithm
regimes/ro/org_identities.go	Organization identity types (CUI, CNP) with validation and normalization
regimes/ro/bill_invoice.go	Invoice validation rules for B2B, B2C, and simplified invoices
regimes/ro/corrections.go	Correction document types (credit-note, debit-note, corrective)
regimes/ro/ro_test.go	Comprehensive tests for regime registration and configuration
regimes/ro/tax_identities_test.go	Tests for CUI/CIF validation including edge cases
regimes/ro/org_identities_test.go	Tests for CUI and CNP validation and normalization
regimes/ro/bill_invoice_test.go	Invoice validation tests covering all invoice types and scenarios
regimes/ro/corrections_test.go	Tests for credit and debit note validation
regimes/ro/README.md	Comprehensive documentation of Romanian tax regime requirements
regimes/regimes.go	Registration of RO regime in global regime list
data/regimes/ro.json	Regime data in JSON schema format
data/schemas/tax/regime-code.json	Added RO to regime codes schema
examples/ro/*.yaml	Example invoices demonstrating various scenarios
examples/ro/out/*.json	Generated JSON output from example invoices
CHANGELOG.md	Changelog entry documenting the new regime

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[samlown]

Great submission! Thanks! There is a little too much validation on the basic structure of the invoice which should be offloaded to an addon in the future, we've found its best to keep the regime as flexible as possible, and add more restrictions through addons.

The Org and Tax identity approach is great. We've not done that for other countries, but it is useful to be able to re-use and validate IDs that may or may not be used for taxes, depending on the context.

[samlown]

This looks very complete, but we don't normally add this level of validation at the Regime level and instead define an "addon" for a local format or tax agency.

[adlrocha]

I didn't go in depth into how addons worked as I was implementing the regime. I can look into it and move some of the validation logic to an addon if that's useful.

[samlown]

Are corrective invoices supported in RO? Not all countries have support for this, the lack of a translation suggests not.

[adlrocha]

You are right, good catch! Corrections are indeed not supported, you need to issue a credit or debit note referencing the original invoice. I got inspiration from the implementation of other regimes and completely forgot to remove the unsupported correction. Pushed the fix.